Current structures for detachably securing tool bits to an output shaft of a device, such as the rotary output shaft of a power tool, are generally one of two types; namely, collet types which utilize a collet having integral, resilient jaw members to secure a tool, and chuck types which utilize a plurality of separate, sliding jaw members to secure a tool. However, each of these two types of currently existing tool bit holders has significant shortcomings.
Namely, those of the collet type are quite limiting in the range of tool bit shaft diameters which they can receive or accommodate, but are, however, relatively inexpensive to produce and relatively simple in construction. Those of the chuck type can accommodate a significantly wider range of tool bit shaft diameters, but are, however, relatively expensive to produce and relatively complex in construction. The relative complexity of construction of chuck-type structures results in unacceptably frequent malfunction of chuck type structures, such as due to debris interfering the springs utilized to bias the separate clamping jaw members, or interference of the sliding movement required of the separate clamping jaw members.
Accordingly, there remains a need for a tool bit holder suitable for attachment to the rotary output shafts of small, power-driven devices which can accommodate the wide range of tool bit sizes associated with chuck-type structures, and which also has the greater reliability and lower cost of production associated with collet-type structures. Also, there remains a need for a collet type tool bit holder which can accommodate a wider range of tool bit shaft diameters, without the requirement of interchanging one or more components of the tool holder, such as changing between two or more collets, than is obtainable with currently existing collet-type tool holders.